Escape device for aircraft

Abstract: An escape device (1) for aircrafts having a pair of gas bags (3) and a slide member (4) joined to the gas bags. The escape device provides a high resistance to radiation heat and reliable bonding between the sheet members. The sheet member forming the gas bags and the slide member includes a substrate of fabric and covering layers of thermosetting elastomer containing a flame retardant. The sheet members forming the gas bags are bonded together before the covering layer of one of the sheet members hardens completely. A protective layer is provided on the outer surface of the joint portion between the sheet members to reflect radiation heat.

Description: This invention relates to a device installed on an aircraft for use as an escape slide or a life-saving raft in case of emergency such as emergency landing. Unexamined Japanese Patent Publication 59-152851 discloses an escape device for an aircraft of this type. It is normally stored in an aircraft in a folded state. In case of emergency, it is inflated by blowing gas thereinto to form a slide. As shown in present Fig. 1, this device comprises an opposed pair of gas bags 1 formed of flexible sheets into a cylindrical shape, and a sheet member provided between and secured to the gas bags 1. Its top surface serves as a slide surface 2. By inflating the gas bags by blowing gas thereinto, this device can be used as a slide. In case the aircraft has landed on the sea, this device can be used as a life raft by detaching it from the aircraft because the gas bags 1 have buoyancy. When using the device as a slide, the gas bags 1 serve to keep the shape of the slide. Thus, they have to have a sufficient rigidity. If the device is used as a life raft, the bags serve as floats for keeping the raft afloat on the water. It is therefore essential that the joint portions of the sheets forming the gas bags stably exhibit high bond strength and air-tightness. If a fire breaks out in an emergency situation, the escape device will be exposed to very high radiation heat. The joint portions of the sheets forming the gas bags are thus required to maintain high bond strength even under high-temperature conditions. For this purpose, as shown in present Fig. 10, Unexamined Japanese Patent Publication 59-152851 proposes to form the gas bags and the slide surface from sheet members 41 having covering layers 42, 43 made of a thermoplastic polymer. The sheet members 41 are bonded together through a heat-resistant adhesive. On the outer side of the bonded portion is applied a protective layer 44 made of a thermoplastic polymer containing metallic particles to reflect the radiation heat and minimize the temperature rise at the joint portion. Such a conventional escape device has the following problems. (1) If exposed to radiation heat, the covering layers 42, 43 of the sheet member 41 will be heated and soften, thus lowering the strength of the sheet. If exposed to high radiation heat, the thermoplastic polymer forming the sheet members may melt and flow. Since the gas pressure in the gas bags rises when heated, the thermoplastic polymer of the covering layer may be pushed outwards by the inner pressure. In an extreme case, the bag might be broken. Air-tighteness is lost if this happens. If the covering layer 43 forming the slide surface, which is also made from a thermoplastic polymer, is heated and softens, the frictional resistance of the slide surface may increase sharply to such an extent that the escape device loses its function as a slide. Furthermore, if the sheet member 41 is formed solely of a nylon fabric or a covering layer of thermoplastic polymer, it may catch fire if a fire breaks out near the escape device. In an extreme case, the entire escape device may be burned down. (2) Since an adhesive is used to bond the sheet members together, poor quality of the adhesive used or an awkward job when applying the adhesive or when bonding the sheet members together would affect the bonded state and bond strength. For example, if voids are present between the sheet members bonded together, they may expand when heated, thus quickening the peeling at the bonded portion. Since it is difficult to check the bond strength between the sheet members by subjecting them to destruction tests or sampling tests, it is essential to strictly control the quality of the adhesive used and the work for applying adhesive and bonding the sheets. Thus, the work efficiency is extremely low. (3) The protective layer 44, formed from a thermoplastic polymer, turns into a dense solid layer when hardened and shows a high heat conductivity. The metallic particles, which are mixed to reflect radiation heat, act as a good heat conductor. Thus, if exposed to radiation heat, the protective layer tends to conduct a large amount of heat to the sheet member and thus cannot restrain temperature rise at the bonded portion. (4) The sheet members 41, covered with a thermoplastic polymer, are joined together with an adhesive. Thus, if the thermoplastic polymer is heated and softens, the bond strength will drop sharply. The bonded state may be broken as a result. Especially if the joint portions are exposed to extremely high radiation heat, the thermoplastic polymer forming the protective layers of the sheet members may melt and flow out from the joint portions as shown by chain line in Fig. 10 even if the adhesive used is a heat-resistant urethane polymer. The joint portions may be broken if this happens. In an arrangement in which the protective layer is formed by applying a molten polymer to the sheet members, if the polymer is applied unevenly, radiation heat will be reflected unevenly, too. Especially if the joint portions are long, it is very difficult to apply a polymer evenly. Workability is thus low. It is an object of the present invention to provide an escape device for use in an aircraft which can withstand high radiation heat, which retains high bond strength at the joint portions at least for a period necessary for passengers to escape from the aircraft and which can be reliably used as a slide and a life raft. Another object of this invention is to provide a method of manufacturing such an escape device in which the sheet members themselves or the sheet members and the protective films can be joined together securely and reliably. According to this invention, there is provided an escape device for an aircraft comprising a pair of gas bags each formed of sheet members joined together into a cylindrical shape and arranged parallel to each other, and a sheet member forming a sliding surface and disposed between and joined to the pair of gas bags, the gas bags being inflatable by blowing gas thereinto to form a slide, characterized in that the sheet members forming the gas bags being covered with a thermosetting elastomer. The thermosetting elastomer should preferably contain a flame-retardant so that it has self-extinguishability. In the second arrangement of the invention, the joint portions between the sheet members forming the gas bags are joined together partially or entirely by stitching. In the third arrangement of the invention, each joint portion between the sheet members forming the gas bags has its inner surface covered with a seal layer made from a thermosetting elastomer. The seal layer may be provided only on the portion at which the sheet members are stitched together. In the fourth arrangement of the invention, each joint portion between the sheet members forming the gas bags has its outer surface covered with a protective layer capable of reflecting radiation heat. The protective layer may be a tape made from an thermosetting elastomer containing metallic powder or comprise a reflecting layer containing metallic powder and a non-dense layer having evenly dispersed fine pores. The protective layer may be formed only on the portion at which the sheet members are stitched together. From another aspect of the invention, there is provided a method of manufacturing an aircraft escape device, the method comprising the steps of forming a pair of cylindrical gas bags by bonding together sheet members covered with an elastomer, bonding a sheet member covered with an elastomer to the pair of gas bags, which are arranged parallel to each other, thereby forming a sliding surface, and bonding a protective film covered with an elastomer to the outer surface of each joint portion between the sheet members forming the each gas bag, characterized in that the sheet members forming the gas bags are covered with a thermosetting elastomer and are bonded together before the covering layer of at least one of the sheet members hardens completely. Preferably, the sheet members and the protective films are bonded together before the elastomer layer provided on at least one of the sheet member and the protective layer hardens. Since the covering layers of the sheet members are formed from a thermosetting elastomer, they will harden if heated when exposed to radiation heat. They will never melt or flow, so that they will not be broken. Further, since the covering layers do not soften, the sheet members are kept in the bonded state, so that the gas bags can be sealed airtightly. Also, the frictional resistance of the slide surface is kept low. In the second arrangement of the invention, the sheet members are joined together by stitching. This eliminates such uncertain factors as poor quality of the adhesive and poor jobs when applying adhesive and laminating sheets. This increases reliability in joining work. In the arrangement in which the sheet members are joined together by stitching, the joint portions will never soften even if heated unlike joint portions which utilize adhesive. Thus, they keep high bond strength, so that the gas bags can maintain their original shape even if the air-tightness at the joint portions changes slightly. The entire device can thus keep its shape as a slide or a life raft. In the third arrangement, the joint portions of the gas bags have their inner surface covered with a seal layer. If the gas bags are heated and their gas pressure increases, the seal layers are pressed against the sheet members, thus sealing the joint portions. The joint portions are thus kept airtight. The seal layers applied to the stitched portions serve to prevent the gas from leaking through the gaps around the stitching yarns. In the fourth arrangement, the protective layers provided on the stitched portions serve to reflect radiation heat and thus to curb temperature rise of the stitched portions. Such a protective film may be made up of a reflecting layer and a non-dense layer. Air gaps dispersed uniformly in the non-dense layer serve to restrain heat conduction from outside of the protective film to the boned portion. Such a non-dense layer is preferably made of an elastic material so that it is resiliently deformable when the sheet members are folded. For example, it may be a spongy or fabric material, which is desirable because it is possible to adjust its thermal conductivity or the thickness of the protective film by changing the fabric structure or the pore size of the sponge. On the other hand, according to the manufacturing method of this invention, the sheet members are laminated together before the covering layers are hardened, so that the sheet members are bonded together strongly. By using a crosslinking type adhesive, partial crosslinking reaction will occur between adhesive and the unhardened covering layer. This further increases the bond strength. Other features and objects of the present invention will become apparent from the following description made with reference to the accompanying drawings, in which: Fig. 1 is a perspective view showing the escape device for an aircraft according to the present invention; Fig. 2 is a sectional view showing the structure of the sheet member forming the gas bag of the first embodiment; Fig. 3 is a sectional view of the sheet member forming the sliding member of the same; Fig. 4 is a sectional view showing the joint portion between the sheet members of the same; Figs. 5(a) to 5(c) are sectional views showing the internal structure of the protective layer; Fig. 6 is a perspective view of the gas bag used in the durability test; Fig. 7 is a view showing the test device used in the durability test; Fig. 8 is a sectional view showing one example of stitch structure of the sheet members of the second embodiment; Fig. 9 is a sectional view showing another stitch structure of the same; and Fig. 10 is a sectional view showing the joint structure of conventional sheet members. (First Embodiment) The escape device of the first embodiment comprises cylindrical gas bags 1 formed of sheet members 3 and arranged parallel to each other, and a sheet member 4 forming a flat slide surface 2 and having its both sides bonded to the gas bags 1. The sheet members 3 for the gas bags 1 comprise, as shown in Fig. 2, a substrate 5 of a flexible fabric and covering layers 6 and 7 covering the inner and outer surfaces of the substrate 5, respectively. The inner covering layer 6 is made from an ether type thermosetting elastomer formed by adding a flame-retardant to a polyurethane polymer to make it self-extinguishing. The outer covering layer 7 is formed by adding metallic powder such as aluminum powder to the above-mentioned ether type thermosetting elastomer containing a flame-retardant. By adding metallic powder, this layer can reflect radiation heat. On the other hand, the sheet member 4 forming the slide surface 2 comprises, as shown in Fig. 3, a substrate 8 formed of a flexible fabric and covering layers 9 and 10 covering the inner and outer surfaces of the substrate 8, respectively. The inner covering layer 9 is, as with the sheet members 3 forming the gas bags 1, made from an ether type thermosetting elastomer formed by adding a flame-retardant to a polyurethane polymer to make it self-extinguishing. The outer covering layer 10 is made from a thermosetting elastomer containing metallic powder for better sliding action and a conductive material to give the slide surface electrical conductivity. A flame-retardant may be added to the covering layer 10, too. As shown in Fig. 4, the sheet member 3 forming each gas bag 1 has its opposed ends overlapped by a predetermined width. The overlapped portions are bonded together (as shown by lines 12 in Fig. 1) through an adhesive 11 of a heat-resistant crosslinking polyurethane polymer. In order to bond the ends of the sheet member 3, they are heated and laminated together with the adhesive interposed therebetween, before the thermosetting elastomer in the covering layers 6, 7 hardens completely. Seal tapes 13 are bonded to the sheet members 3 along the joint lines 12 from inside the gas bags 1. The seal tapes 13 are formed by cutting a thermosetting elastomer. In the same manner as in bonding the sheet members 3 together, they are bonded to the sheet members 3 by means of a crosslinking adhesive 11 before the thermosetting elastomer hardens completely. The seal tapes 13 serve to prevent gas leakage through the overlapped ends of the sheet members 3. They are bonded so as to cover the overlapped end portions of the sheet members 3 and the connecting portions between the gas bags 1 and the sheet members 3 forming the ends of the gas bags 1. The outer side of each joint portion 12 of the sheet members 3 is divided into three parts to which are bonded protective films 14, 15 and 16, respectively, which have different internal structures from each other. Of the three different kinds of protective films, the protective film 14 comprises, as shown in Fig. 5(a), a non-dense layer 17 having a fabric structure with fine pores present uniformly, a covering layer 18 covering the inner surface of the non-dense layer 17, and a reflecting layer 19 covering the outer surface thereof. The covering layer 18 is made from a thermosetting elastomer containing e.g. a polyurethane polymer as a base component. The reflecting layer 19 is formed by mixing metallic powder such as aluminum powder into the above-mentioned thermosetting elastomer. As shown in Fig. 5(b), the protective film 15 has a non-dense layer 20 made from an urethane sponge having numerous continuous air gaps. On both sides of the non-dense layer 20 are provided a covering layer 17 and a reflecting layer 18, which are the same as used in the protective film 14. The protective film 16 comprises, as shown in Fig. 5(c), a non-dense layer 20 made of a urethane sponge and a reflecting layer 19 made of a thermosetting elastomer containing metallic powder. The protective films 14, 15 and 16 are cut beforehand into tapes and, with a crosslinking adhesive 11 applied to their inner surfaces and the outer surface of the sheet members 3, bonded to the sheet members 3 so as to cover the entire width of the bonded portions. The inner covering layers 18 of the protective films 14 and 15 are heated and, before the thermosetting elastomer forming the layers 18 hardens completely, the films 14, 15 are bonded to the sheet members 3. The protective film 16 having no inner covering layer, is bonded to the sheet members 3 after applying a larger amount of crosslinking adhesive thereto than to the other films. The sliding surface 2 and the gas bags 1 are bonded together by bonding both ends of the sheet member 4 forming the sliding surface 2 to the underside of the pair of gas bags 1 through a crosslinking adhesive. The sheet member 4 is bonded with its covering layer 10 having electrical conductivity facing up for better sliding property. Next, we will discuss its advantages. Since the covering layers 6, 7, 9 and 10 of the sheet members 3, 4 are made from a thermosetting elastomer, they will never melt or flow even if exposed to high radiation heat. Thus, the sheet members are kept airtight and the air bubbles, if any, trapped in the covering layers will little inflate. Moreover, since the covering layers never flow, they can be used as adherers without the possibility of the joint portions being destroyed. Also, since the covering layer 10 of the sheet member 4 forming the sliding surface never softens, the frictional resistance on the surface will never change, so that people can slide down it easily. Since the thermosetting elastomer forming the covering layers contains a flame-retardant and thus have self-extinguishability, even if the members 3, 4 should catch fire, the fire will die down soon and not spread. Since the covering layers are formed from a thermosetting elastomer containing a polyurethane polymer as a base component, they are relatively lightweight and have high wear resistance and good bond property. Furthermore, since polyurethane polymer can be hardened at room temperature by adjusting the hardening agent used, such layers can be manufactured easily. An ether type polyurethane polymer is selected as the polymer forming these layers in the embodiment. Ether type is known to have higher water resistance than an ester type. If the escape device is exposed to radiation heat, it is reflected by the reflecting layers 19 of the protective films 14, 15 and 16 bonded to the joint portions of the sheet members 3. Also, the numerous air gaps present in the non-dense layers 17, 20 in the protective films serve to restrain heat conduction and minimize the amount of heat conducted to the sheet members 3. Since the temperature rises little at the joint portions of the sheet members, the covering layers 6, 7 in the sheet members are less likely to soften or peel off from the adhesive. Thus, the bonded state is maintained stably. Since the opposed ends of the sheet member 3 and the protective films 14, 15 and the sheet members 3 are bonded together before the surface layer of thermosetting elastomer hardens completely, they can be bonded together strongly. Now, we will discuss various experiments conducted to examine the durability of the escape device of the first embodiment. First, we prepared a gas bag having the structure of the first embodiment (hereinafter referred to as Specimen) and a gas bag manufactured according to the teaching of the above-mentioned Japanese Patent Publication 59-152851 (Comparative Example) and they were subjected to durability tests in which they were exposed to radiation heat. The test device used in the test is shown in Fig. 7. It has a pressure container 22 for fitting the gas bags, and an electric heater 23 provided opposite to the pressure container 22. They were mounted on a fixed base 21. To the pressure container 22 are connected a hose 24 for supplying high-pressure air and a pressure gauge 25. The pressure container 22 is a cylindrical member having a diameter of 178 mm and an overall length of 314 mm. As shown in Fig. 6, the gas bags used in the test were cylindrically shaped so that they can be fitted in the pressure container 22. Its end is closed by pressing another sheet member against the end and folding its end. Table 1 shows the structure of the sheet members forming Specimen and Comparative Example and the kinds of adhesives used. In Table 1, the thermosetting elastomer forming the covering layer of Specimen was made from a polyurethane polymer containing Polyol 0265 and Isocyanate 0620 (trade names) made by Sumitomo Bayer Urethane Co., Ltd.. To this polymer base was added a flame-retardant which is a mixture of BT-93W (trade name) made by Ethyl Corporation and antimony trioxide. The seal tapes 13 laminated to the inner surface of the joint portions of the sheet members 3 were made from the same polyurethane polymer as above (thermosetting elastomer) but not containing a flame-retardant. It was formed in tape 1 mm thick and bonded to the sheet member through a crosslinking adhesive. Table 2 shows the detailed structures of the protective films 14, 15 and 16 provided on the outer side of the sheet members of Specimen and of the protective layers provided on the sheet members of Comparative Example. In Table 2, the thermosetting elastomer forming the covering layers 18 and the reflecting layers 19 are made from a polyurethane polymer which is a mixture of Polyol 0265 and Isocyanate 0620 (trade names) made by Sumitomo Bayer Urethane Co., Ltd.. The protective films 14, 15 and 16 are in the form of tapes having a width larger than the width of the joint portions of the sheet members so that they can completely cover the joint portions. They were bonded to the sheet members through a crosslinking adhesive. The bonding of the sheet members 3, between the sheet member 3 and the sealing tape 13, and between the sheet member 3 and the protective films 14, 15 were carried out before the thermosetting elastomers on the mating surfaces harden completely. The adhesive used in Specimen was a polyurethane polymer adhesive which was a mixture of Desmocoll 540 and RE (trade names) made by Sumitomo Bayer Polyurethane. The adhesive used in Comparative Example was Paraprene (trade name) made by Japan Polyurethane Industries Co., Ltd.. Both Specimen and Comparative Example were cylindrically shaped with one end closed by another sheet member which was folded along its edge onto the outer periphery of the cylindrical body by the width of more than 75 mm as shown in Fig. 6 and bonded thereto with an adhesive. A protective layer was further wound around and bonded to a folded portion 26. In the durability test, fragments cut from the gas bags of Specimen and Comparative Example were fitted in the pressure container 22 of the test device shown in Fig. 7; air was introduced into the pressure container 22 to increase the internal pressure of the gas bags to 0.182 kgf/cm 2 ; and the electric heater 14 was turned on to radiate heat against the sheet members of the gas bags at the rate of 5.38 kcal/m 2 /sec (2.0 Btu/ft 2 /sec). The gas bags were tested for their performance by measuring the point of time at which the internal pressure decreased sharply as a result of air leakage through pin holes that developed in the sheet members of the gas bags. During the test, when the sheet members of Comparative Example, which were covered with a thermoplastic polymer, were heated for about 150 sec., the covering layer melted and the thus molten covering layer flowed due to the gas pressure in the bag. As a result, the sheet members were broken, causing gas leakage. In contrast, the covering layer of Specimen never softened or flowed, so that air-tightness was kept, though its surface turned brownish after the sheet members were heated for 990 sec. At the joint portions of the sheet members of Comparative Example, the covering layer of thermoplastic polymer melted and flowed when the sheets were heated for about 150 sec. The bond strength thus dropped, resulting in separation at the joint portions. The sheet members forming the gas bag of Specimen showed no such separation at the joint portions of the sheet members or at the joint portion between the sheet member and the protective film, even after the sheet members were heated for 300 sec. As a second durability test, we subjected the gas bags of Specimen and Comparative Example to heat resistance test under ASTM Standards D4372. During the test, the gas bag of Specimen, which contained a flame-retardant in the covering layer, scarcely caught fire, while Comparative Example, which contained no flame-retardant, caught fire and the fire spread until the entire specimen was burned down. As a third durability test, we prepared a sheet member according to the present invention which has a substrate 5 of nylon fabric covered with an ether type polyurethane polymer, and a sheet member as a comparative example having the same substrate as above which is covered with an ester type polyurethane polymer. They were subjected to a hydrolysis test in which the sheet members were exposed to an environment kept at a humidity of 95% or higher and a temperature of 58 C for 50 days. In the test, the covering layer of the sheet member as comparative example decomposed and disappeared. The sheet member according to the present invention kept high air-tightness, though its covering layer softened slightly. (Second Embodiment) Figs. 8 and 9 show the second embodiment in which each gas bag was made by stitching the overlapped portions of the sheet members. Namely, in this embodiment, the sheet members 3 of each gas bag 1 were connected together by overlapping their opposed ends and stitching them together with a heat-resistant yarn 31 such as polyaramid yarn, nylon or polyester yarn. The joint line on the inner side of each gas bag had a structure shown in Fig. 8, while the joint line on the outer side had a structure as shown in Fig. 9. The structure shown in Fig. 8 is formed by stitching overlapped ends 32 of the sheet members 3 with the stitching yarn 31 in two rows and then applying a seal tape 13 to the inner surface of each stitched portion. In order to prevent gas leakage through around the yarns 31 and the overlapped ends of the sheet members 3, this seal tape 13 is bonded to the sheet members in such a way that it covers the surroundings of the exposed portion of the yarn 31 and the ends of the sheet members. On the outer surface of each stitched portion is laminated a protective layer 33 for reflecting radiation heat. The protective layer 33 is formed by heating a thermosetting elastomer containing metallic powder into a liquid state and applying the liquid elastomer to the stitched portion together with a crosslinking type adhesive. The protective layer 33 is provided in order to protect the stitching yarn 31 against radiation heat and to prevent the gas from leaking through gaps formed around the yarn 31. It is laminated on the stitched portion so as to cover the exposed portion of the stitching yarn 31 and its surrounding area. The protective layer may be a tape. The structure shown in Fig. 9 is formed by bending the ends of the sheet members 3 at a right angle, butting them together and stitching the overlapped portions together with a stitching yarn 31 in two rows. The seal tape 13 formed of a thermosetting elastomer is bonded to the inner side of the stitched portion so as to cover the surroundings of the exposed portion of the stitching yarn 31 and the overlapped ends of the sheet members that extend from end to end of the gas bag 1. Further, a protective layer 35 in the shape of a tape is applied to the outer side of the overlapped ends of the sheet members 3. This protective layer 35 is formed by cutting a thermosetting elastomer containing metallic powder into the shape of a tape. It is laminated on the surfaces of the sheet members 3 through a crosslinking type adhesive 11. This protective layer 35 does not directly cover the stitching yarn 31. But if the overlapped portions 34 are pulled apart from each other, an opening formed will be covered by the protective layer 35, so that the stitching yarn will never be exposed to the atmosphere. Thus, the protective layer serves to protect the stitched portion against radiation heat. The gas bags 1 and the sheet member 4 having the sliding surface 2 are joined together by bonding the side edges of the sheet member 4 to the underside of the gas bags 1 by means of a crosslinking adhesive as in the first embodiment. The sheet member 4 and the gas bags 1 are bonded together through an adhesive, not by stitching, because the bonded portions thus formed will not affect the air-tightness of the gas bags 1. Even if the bonded state of the sheet member 4 should change slightly, the overall shape of the device changes little, so that it can be used as a slide or a life raft. Since the sheet members 3 forming the gas bags are joined together to form a gas bag by mechanical means, i.e. by stitching, it is possible to eliminate unreliable factors such as errors in the work such as applying an adhesive or laminating tapes. By using a stitching yarn 31 made from a highly crystallizable, high-melting point, high-strength, fibrous, high-polymer material, such as polyaramid, nylon or polyester, it is possible to markedly improve the bond strength and heat resistance. Thus, even if the sheet members and their covering layers are heated and soften, the bonded state can be maintained, so that the gas bag can retain its shape stably. The seal tape 13 laminated on the inner surface of the stitched portion serves to prevent the inside gas from leaking out along the stitching yarn 11 or through any defects such as pin holes formed in the ends of the sheet members 3 and the covering layers 7, 10. The gas bag 1 can thus keep high air-tightness. The protective layers 33, 35 which cover the outer surface of the stitched portion serve to curb temperature rise by reflecting the radiation heat and also serve as a seal for preventing gas leakage along the stitching yarn 11. Since the protective layers 33, 35 are made from a thermosetting elastomer, they exhibit high heat resistance and elasticity. Due to the high elasticity, they can be easily folded at the joint portions. In Figs. 8 and 9, we showed structures in which the ends of the sheet members 3 are overlapped and stitched together. The overlapped ends may be bonded together through a crosslinking type adhesive before stitching them together. By bonding the ends beforehand, stitching will be easier because they have been fixed. Also, the adhesive layer serves as a seal for preventing air leakage through the overlapped ends of the sheet members. This layer also serves to increase the bond strength. In the second embodiment, the outer and inner joint portions of the gas bags have different structures as shown in Figs. 8 and 9. But they may have the same structure, i.e. one of the two structures shown in Figs. 8 and 9. The sheet members 3 may be stitched together only along the outer joint lines or only at one end of the inner and outer joint lines nearer to the body of the airplane, because these portions are more likely to be exposed to radiation heat. At the other portions, the sheet members may be joined together by adhesive bonding. Such a structure is more heat-resistant than a structure in which the sheet members are joined together solely by adhesive bonding. We prepared a gas bag by stitching two sheet members together in the manner shown in the second embodiment and a gas bag manufactured according to the teaching of Japanese Patent Publication 59-152851 and they were subjected to a durability test in which they were exposed to radiation heat. The test device used in the test is shown in Fig. 7. The gas bags used in the test were cylindrically shaped so that they can be fitted in the pressure container 22. Their ends are closed by use of another sheet, the end of which is folded back. Table 3 shows the structure of the sheet members and the protective layers forming the gas bags. In Table 3, the thermosetting elastomer forming the covering layer and the protective layer of the gas bag having the stitched structure was made from a polyurethane polymer containing Polyol 0265 and Isocyanate 0620 (trade names) made by Sumitomo Bayer Urethane Co., Ltd.. One of the joint lines of the gas bag at one side had the structure shown in Fig. 8. Along this line, sheet ends were overlapped by a width of 40 mm and the overlapped ends were stitched together with a nylon yarn in two rows which were spaced about by 10 mm. The joint line at the other side had the structure shown in Fig. 9. Along this line, sheet ends were overlapped by a width of 30 mm and the overlapped ends were stitched together with a nylon yarn in two rows which were spaced apart from each other by 5 mm. A seal tape 13 was applied to the inner surface of each stitched portion through an adhesive. It was formed by cutting a polyurethane polymer-based thermosetting elastomer into a 1-mm thick tape. In the durability test, the gas bags having the stitched structure and those having the bonded structure were fitted in the pressure container 22 of the test device shown in Fig. 7 and, in the same manner as in the above-described tests, air was introduced into the pressure container 22 to increase the internal pressure of the gas bags to 0.182 kgf/cm 2 ; and the electric heater 23 was turned on to radiate heat against the sheet members of the gas bags at the rate of 5.38 kcal/m 2 /sec (2.0 Btu/ft 2 /sec). During the test, when the gas bag having the bonded structure was heated for about 150 sec., peeling occurred at the bonded portions of the sheet members and the internal pressure of the bag dropped sharply. In contrast, the gas bag having the stitched structure suffered no reduction in internal pressure even after it was heated 990 sec. Specimen Comparative example Sheet member Substrate Nylon fabric (2 x 2 basket weave of 210 denier nylon yarn) Nylon fabric (Plain weave of 210 denier nylon yarn) (Density) (41+41) warps x (41+41) wefts /inch 82 warps x 52 wefts /inch (Weight) 160 g/m 2 130 g/m 2 Covering layer 〈inner〉 Thermosetting elastomer Thermoplastic polymer (Weight) 80 g/m 2 70 g/m 2 Covering layer 〈outer〉 Thermosetting elastomer containing aluminum powder Thermoplastic polymer containing aluminum powder (Weight) 30 g/m 2 30 g/m 2 Adhesive Polyurethane polymer crosslinking type adhesive Urethane polymer adhesive Specimen Protective layer 14 Non-dense layer Nylon fabric Covering layer Thermosetting elastomer (Weight 100 g/m 2 ) Reflecting layer Thermosetting elastomer containing aluminum powder (Weight 50 g/m 2 ) Protective layer 15 Non-dense layer Urethane sponge Covering layer Thermosetting elastomer (Weight 100 g/m 2 ) Reflecting layer Thermosetting elastomer containing aluminum powder (Weight 50 g/m 2 ) Protective layer 16 Non-dense layer Urethane sponge Reflecting layer Thermosetting elastomer containing aluminum powder (Weight 50 g/m 2 ) Comparative example Protecting layer Thermoplastic polymer containing aluminum powder Stitching structure Bonded structure Sheet member Substrate Nylon fabric (2 x 2 basket weave of 210 denier nylon yarn) Nylon fabric (Plain weave of 210 denier nylon yarn) (Density) (41+41) warps x (41+41) wefts /inch 82 warps x 52 wefts /inch (Weight) 160 g/m 2 130 g/m 2 Covering layer 〈inner〉 Thermosetting elastomer Thermoplastic polymer (Weight) 80 g/m 2 70 g/m 2 Covering layer 〈outer〉 Thermosetting elastomer containing aluminum powder Thermoplastic polymer containing aluminum powder (Weight) 30 g/m 2 30 g/m 2 Protective layer (Structure) Thermosetting elastomer containing aluminum powder Thermoplastic polymer containing aluminum powder Stitching yarn Nylon yarn of 1260 denier ― Adhesive ― Urethane polymer adhesive

Claims: An escape device for an aircraft comprising a pair of gas bags (1) each formed of sheet members (3) joined together into a cylindrical shape and arranged parallel to each other, and a sheet member (4) forming a sliding surface and disposed between and joined to said pair of gas bags (1), said gas bags (1) being inflatable by blowing gas thereinto to form a slide, characterized in that said sheet members (3) forming said gas bags (1) being covered with a thermosetting elastomer. An escape device as claimed in claim 1 wherein said thermosetting elastomer contains a flame-retardant to make said gas bags (1) self-extinguishing. An escape device as claimed in claim 1 or 2 wherein said sheet members (3) forming said each gas bag (1) are joined together at least partially by stitching. An escape device as claimed in any of claims 1-3 wherein each joint portion between said sheet members (3) forming said each gas bag (1) has inner surface thereof covered with a seal layer (13) made from a thermosetting elastomer. An escape device as claimed in claim 4 wherein said seal layer (13) is provided only on the portion at which said sheet members (3) are joined together by stitching. An escape device as claimed in any of claims 1-5 wherein said each joint portion (12) between said sheet members (3) forming said each gas bag (1) has outer surface thereof covered with a protective layer (14, 15, 16) capable of reflecting radiation heat. An escape device as claimed in claim 6 wherein said protective layer (14, 15, 16) is in the form of a tape made from a thermosetting elastomer containing metallic powder. An escape device as claimed in claim 6 wherein said protective layer (14, 15, 16) comprises a reflecting layer (19) containing metallic powder and a non-dense layer (17, 20) having evenly dispersed fine pores. An escape device as claimed in any of claims 6-8 wherein said protective layer (14, 15, 16) is formed only on the portion at which said sheet members (3) are joined together by stitching. A method of manufacturing an escape device for an aircraft, said method comprising the steps of forming a pair of cylindrical gas bags (1) by bonding together sheet members (3) covered with an elastomer, bonding a sheet member (4) covered with an elastomer to said pair of gas bags (1), which are arranged parallel to each other, thereby forming a sliding surface, and bonding a protective film (14, 15, 16) covered with an elastomer to the outer surface of each joint portion (12) between said sheet members (3) forming said each gas bag (1), characterized in that said sheet members (3) forming said gas bags (1) are covered with a thermosetting elastomer and are bonded together before the covering layer (6, 7) of at least one of said sheet members (3) hardens completely. A method of manufacturing an escape device for an aircraft as claimed in claim 10 wherein said sheet members (3) and said protective films (14, 15, 16) are bonded together before the elastomer layer (7; 18) provided on at least one of said sheet member (3) and said protective layer (14, 15, 16) hardens.

Inventors: KASHIHARA HIDEKI, NISHIMURA AKIRA, KASHIHARA, HIDEKI, NISHIMURA, AKIRA, KASHIHARA, HIDEKI, C/O OSAKA WORKS, NISHIMURA, AKIRA, C/O OSAKA WORKS
Applicants: SUMITOMO ELECTRIC INDUSTRIES, SUMITOMO ELECTRIC INDUSTRIES, INC.
Application year: 1994
Main classification: B64C25
IPC codes: B64D25